1. Field
Aspects of embodiments of the present invention relate to a pixel and an organic light emitting display device using the same.
2. Description of the Related Art
Various flat panel displays (FPDs) with reduced weight and volume as compared to cathode ray tube (CRT) displays have been developed. The FPDs include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic light emitting display device.
Among the FPDs, the organic light emitting display device displays an image using organic light emitting diodes (OLED) that generate light by re-combination of electrons and holes. The organic light emitting display has a high response speed and low power consumption.
The organic light emitting display includes a plurality of pixels arranged at crossing regions of data lines, scan lines, and power lines in the form of a matrix. In general, each of the pixels includes an OLED, at least two transistors including a driving transistor, and at least one capacitor.
While the organic light emitting display device has low power consumption. However, an amount of current that flows to the OLED varies with the threshold voltage variation of the driving transistor included in each of the pixels, hence non-uniform displaying occurs. That is, properties of the driving transistor included in each of the pixels vary with the manufacturing process. Generally, it is difficult to manufacture all transistors of the organic light emitting display device to have the same properties using current manufacturing technology. Therefore, the threshold voltage variation of the driving transistors occurs.
In order to solve the above-mentioned problems, a method of adding a compensation circuit having a plurality of transistors and capacitors to respective pixels has been proposed. Each of the compensation circuits included in the respective pixels stores (or charges) a voltage corresponding to the threshold voltage of the driving transistor to compensate variation of the driving transistor.
In order to realize a 3D image, a method of driving the conventional 60 Hz period by dividing the 60 Hz period into 240 Hz periods has been proposed. However, in the case of the high speed driving higher than 240 Hz, the charging period of the threshold voltage of the driving transistor becomes shorter, and therefore it is not possible or very difficult to compensate for the threshold voltage of the driving transistor.